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Bridging the Gap from Crop Improvement to Production

Keith Warren
Director of Product Development
J. Frank Schmidt & Son Co.

A paper from the Proceedings of the 12th Metropolitan Tree Improvement Alliance Conference (METRIA 12), Landscape Plant Symposium: Plant Development And Utilization, held in Asheville, NC, May 23-25, 2002, co-sponsored by the North Carolina State University, North Carolina Division of Forest Resources, USDA Forest Service Southern Region, North Carolina Landscape Association, North Carolina Association of Nurserymen, The Landscape Plant Development Center, The North American Branch of The Maple Society, and The International Ornamental Crabapple Society.

Over the years, the nursery business has become more complex, sophisticated and competitive. Along with this, diversity of plants and customer service have increased greatly. The tree business was once dominated by seedling sales; now cultivars make up approximately 90% of our sales. Thirty years ago, our company was largely a production company: we grew our crop and one salesman took the orders. Today, we are much more of a full service company, with regional sales representatives across the country and an office staff with specialization in sales, service, and marketing. We also now have a program of testing and evaluation of new tree cultivars, as well as an active breeding and selection program aimed at crop improvement.

Improved tree cultivars have been developed by breeding and selection work in the scientific community (universities, arboreta, U.S.D.A.) and by a number of nurseries. Trees introduced by the scientific community are commonly selected on the basis of genetics or characteristics of an outstanding mature specimen. Trees introduced by commercial nurseries tend to be selected with emphasis on production characteristics in the nursery.

Because of this, trees introduced by the scientific community sometimes fail to meet the practical needs of production nurseries. They may be too difficult to propagate, grow too slowly, or fail to branch symmetrically. Likewise, nursery introductions usually look perfect when young, but sometimes disappoint as they mature.

To bridge the gap between crop improvement and production, and finally landscape performance, we carry out a many phased testing and evaluation program. When a new cultivar is first received from an outside source, we begin by propagating it in small plots. Generally, we repeat this test propagation for three years. By doing so, we determine if the cultivar can be propagated at a commercially acceptable rate and build up stock for potential production. We grow each group of trees in a production field along side similar cultivars of the same or closest species. We are then able to evaluate nursery growth characteristics side by side with existing cultivars.

A potential new cultivar must compete for "shelf space" in our catalog. It is a crowded and competitive market between cultivars. For example, we presently grow 50 cultivars of Malus. A new one has to be better, and often has to displace an older cultivar.

Following field growing, the potential introduction is planted out on 6' X 12' spacing in an evaluation block, where it can grow 5 to 10 years until crowding becomes a problem. These trees are grown under harsher condition than typical for nursery stock. After the first season, there is very limited use of water, fertilizer, or pruning. No fungicides or insecticides are applied. They are periodically evaluated throughout the year.

The timing of evaluations is based on the critical aspects of the potential cultivar. A crabapple must have beautiful flowers, disease resistant summer foliage, and excellent fall fruit. A maple must have clean summer foliage, outstanding form, and good fall color. These are the expectations of the marketplace. An Acer rubrum or A. saccharum cultivar without excellent fall color will never make it in the market, no matter how good its other characteristics may be.

It is generally during the time when trees are growing to larger size in the evaluation block that the decision is made to put the tree into production. There is no set time frame to this process, and the testing of propagation, nursery growth, and the evaluation plot may occur simultaneously. Information from the developer of the plant and any other regional test plot is combined with knowledge obtained through our own testing program. The decision to produce a new plant is always based on market place considerations and is always competitive. A new cultivar of Malus must fight for market share against the 50 we presently grow; new cultivar of Maackia faces only a field of one.

In testing a new cultivar, it is evaluated on many characteristics, the most important of which are summarized below:

Practical Characteristics

Horticultural Characteristics

A new cultivar needs to be able to obtain a slice of the market. It generally does this in one of four ways. It might be different, better, satisfy a fad, or fill a need. I find that those cultivars that fill an existing need become the most widely accepted and longest lasting. The practical needs of the green industry drive our sales and introduction program. New introductions are expected to be:

Even as and after a new cultivar is introduced, our evaluation program continues. Each new cultivar is planted in the Schmidt Arboretum. These sometimes become the first mature trees of new introductions, and they are watched as they mature. The Schmidt Trial Pack program is used to test for regional adaptability. In the first year of commercial availability, samples of each new cultivar are sent to a group of 40 to 50 regional cooperators. The regional cooperators are distributed geographically across the U.S. mainland. They report back annually regarding plant performance and adaptability, giving us a clear picture where new cultivars are successful and what their limitations will be.

Schmidt now has its own breeding and cultivar development program. In this, I take a very pragmatic approach, attempting to make my efforts fast, effective, low cost, and market oriented. I take advantage of our strengths as a production nursery. While we lack the scientific abilities of academic institutions, our strength is in numbers – specifically our ability to handle and screen large numbers of plants effectively, and at low cost.

Our breeding work is presently taking place in Malus, Acer rubrum, and Acer platanoides x A.trucatum. F1 crosses are made between existing cultivars with desired traits. We select from these as well as the F2 generation of open pollinated seed from the F1s, crosses between F1s, and back crosses to existing cultivars.

We also collect open pollinated seed from desirable cultivars planted near other desirable cultivars, which likely cross pollinate. This results in a large amount of seed which can be screened in our evaluation process.

The screening and evaluation process is best developed for crabapples and serves as an example. In close spaced seedling transplant beds, trees are repeatedly inoculated with apple scab. Only trees showing no scab, mildew, fireblight, or frog eye leaf spot are saved from these beds. These selected seedlings are lined out and grown in a nursery production field. Here they evaluated for nursery growth form, as well as disease resistance. Flowering and fruiting usually occur here and is part of the selection process. After three years of growth, selected trees are moved to a transplant field where they flower and fruit heavily and characteristics are evaluated, along with disease resistance. After two years, the best are moved to a final evaluation plot. At each stage of the selection process, approximately 90% of the trees are culled. This ten fold reduction in plant numbers at each stage of the four stage process means that one in 10,000 original seedlings is likely to emerge as a cultivar for introduction.

We introduce many cultivars to the national nursery trade which are developed by other individuals outside of our company. Usually, these come to us as budwood of an experimental selection. We put these through this multiphase evaluation process over a number of years before deciding if they are worthy of national introduction. If they are, a joint introduction is planned, and any royalties generated by the new cultivar are shared with the originator.

Some of our recent introductions serve as examples of how this process works:

Apollo® Sugar Maple - Acer saccharum 'Barrett Cole' PP10590. This tree was discovered by Bob Cole (Cole Nursery) in an Ohio residential landscape. The original, mature tree forms an extremely tight, narrow pyramid with dense dark green summer foliage and excellent orange-red fall color. Nursery testing showed the tree to be extremely narrow, dense, and semi-dwarf. Slow growth caused concerns about profitability, but its unique form and high value as a mature specimen convinced us to proceed with introduction.

Georgia GemTM Ash - Fraxinus pennsylvanica 'Oconee'. Until now, the green ash cultivars common in the nursery trade originated in the northern part of the species range. Mike Dirr found this cultivar growing in a natural stand in Georgia; he chose it for its dark green, high gloss foliage, good oval shape, and seedless character. He collected budwood for me, but it was too late in the fall for field propagation. Fortunately, I had a couple of ash growing in a greenhouse as part of a production experiment. We budded these successfully. The next year, it became apparent how fortunate we were: the highway department cut down the original tree during construction! The tree performed well in nursery testing and its introduction was quickly decided on, due to the industry need of a green ash cultivar adapted to the heat of the South.

Snowcone® Japanese Snowbell - Styrax japonica 'JFS-D' Snowcone® began as an effort in our nursery to find a selection of outstanding growth habit without suffering from spring bud failure, a Styrax ailment of unknown cause. Gerard Dosba and Guy Meacham of our operation worked together to find and test propagate five outstanding specimens from our field production. I planted propagules of these in my evaluation block. Together, we agreed on 'JFS-D' as the best of the lot, and we applied the trademark name Snowcone® to it because of its cone shaped habit with uniform, fine textured branching.

Wireless® Zelkova - Zelkova serrata 'Schmidtlow'. I selected this tree from a group of large, seedling grown Zelkova serrata showing variation in form. We had recently begun marketing utility line friendly trees (UtilitreesTM) and I was looking for low, flat top, vase shaped trees which would allow both vehicle clearance below and wire clearance above. I found it in Wireless®. An added bonus is the best red fall color I have seen in a Zelkova.

Royal RaindropsTM Crabapple - Malus 'JFS-KW5' P.A.F. This is the first crabapple to come out of my disease resistant seedling selection program. Royal RaindropsTM resulted from open pollinated seed of Golden Raindrops® crabapple. The pollen parent was obviously a red flowered, purple leafed crab, as Royal RaindropsTM combines the cutleaf foliage of its seed parent with magenta-pink flowers and reddish purple foliage. I think it has better summer color and appearance than any other purple foliaged crab. And as an improvement over its seed parent, my testing has shown that Royal RaindropsTM has good resistance to fireblight.

As the nursery and landscape industries have developed, we have seen a continuous need for tree cultivar development and improvement. There are a great many steps, people, and companies between the cross pollination of trees and a successful metropolitan street planting of a new tree cultivar. We try to bridge this gap so that the best new cultivars find their way to the most appropriate city streets.

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Format updated November 3, 2009